Spinal fixation surgery using an implant made of titanium has been widely performed for diseases causing instability of the spine such as spondylosis deformans and spine injuries. The spinal fixation is a surgical procedure in which to insert a titanium implant into the spine to fixate the position of the spine. Especially there occurs, during this kind of surgery, a problem of damaging the blood vessel or nerves by inserting a spinal fixation screw, which is one kind of implant, in an incorrect area of the spine.
In performing a surgical operation using a spinal fixation screw, a method is employed in which to preoperatively plan and check a place to insert the spinal fixation screw by using an X-ray radioscopy device. However, it is difficult by this method to plan an accurate direction of inserting the spinal fixation screw. Therefore, the probability of being able to insert the spinal fixation screw into the spine at an accurate position and in an accurate direction of insertion depends on surgeon's experience. In addition, a virtual navigation system has been used, which is based on an image taken by computed tomography before surgery. However, the problem is that a large error occurs. Patent Document 1 discloses a technique relating to a template for registration for use in a medical navigation system operation.